PT2058584E - Lighting fixtures with led lights for illumination of outside public areas - Google Patents

Abstract

The refractive optical components (6) for the LED's (11) also act as seals to protect the LED's from the weather. The fixture (1) comprises at least one light emitting diode (LED) mounted on a support (4), as well as at least one refractive optical component for guiding the light from the LED towards a surface requiring illumination.

Description

DESCRIPTION

" LIGHTING DEVICES WITH LED LIGHTS FOR ILLUMINATION OF EXTERNAL PUBLIC AREAS " The present invention relates in a first aspect to an illumination device for illumination of external public areas comprising one or more light emitting diodes and corresponding optical refraction elements for guiding light emitted to one or more illumination areas.

A second aspect of the invention relates to a street lamp comprising the lighting device of the first aspect attached to a post.

BACKGROUND ART It is generally known that lighting devices are known as street lamps or street lamps. These street lamps are often equipped with light sources such as steam lamps because of their low power consumption and long service life.

Given the increase in the specific light output per watt of light emitting diodes (LEDs) it is becoming attractive to apply LEDs on such lighting devices. Although effective light output from LEDs is still at present lower than that of steam lamps it is still attractive to apply LEDs here because a greater proportion of the generated light would be used than in the case of steam lamps. Optical refractive elements are then implemented with LEDs, as well as lenses, whose losses are 1 smaller than in the case of the inevitable reflectors used in vapor lamps. There are already known lighting devices for the external illumination of public areas, such as streets, which comprise at least one light emitting diode (LED) fixed on a carrier and an optical LED refraction element, such as a lens, to guide the light emitted to a lighting area on a lighting surface.

Some proposals apply lenses in front of LEDs, but then comprise a separate transparent bottom plate or cover to protect LEDs against environmental influences such as dirt and moisture, but which must also be crossed by the light emitted by the LEDs. the consequence of the use of said separate elements (bottom plate and lenses) increases the cost, at the same time as bending losses occur as the light emitted by the LEDs also crosses both elements. JP2005116182 relates to an electrical lighting device forming a housing, or insulation housing, housing a circuit board with a plurality of LEDs, and also a bottom plate with through apertures, through which the LEDs emit light. On the outer face of said lower plate, called " lens attachment means ", several bulky lenses are fixed, each covering one of the through apertures. Said bulky lenses have a recessed well-shaped inner portion into which a portion of a respective LED enters. The LEDs described in JP2005116182 have flat faces which, when inserted inside the bulky lenses, are 2 perpendicular to the direction of the optical axis of the lenses, and act as faces of light emission.

DISCLOSURE OF THE INVENTION The object of the present invention is to provide an alternative for conventional lighting devices, which provides better performance mainly in relation to their optical arrangements, easier assembly, immunity against environmental influences and heat dissipation.

To this end, the present invention relates, in a first aspect, to an electric lighting device for lighting public areas, the type comprising: a cover and a bottom plate mutually coupled to form a housing, said plate having one or more through apertures; - a holder or circuit board placed within said housing; - one or more LEDs, mechanically attached to said circuit board and electrically connected to the circuit defined therein, to emit light through said apertures; and - one or more optical refracting elements attached to said bottom plate covering said apertures, intended to guide the light emitted by the LEDs to a lighting area on a lighting surface outside said housing.

Contrary to the prior art, particularly JP2005116182 which is considered herein to be the most recent prior art, in the lighting device proposed by the first aspect of the present invention each of the refractive optical elements is secured to the inner face of the lower plate through of the periphery of one of said through openings.

For one embodiment, each of said apertures has a border skirted by its periphery, which surrounds the inner face of the bottom plate and at least one optical refractive element is mounted and laterally retained on said skirted edge. In order to guarantee said immunity to environmental influences, the proposed lighting device comprises at least one seal (for example, made of synthetic material or glass), by aperture mounted between each optical refraction element and each edge circumscribed, around the entire periphery thereof, to seal the interior of said housing against said environmental influences.

For a preferred embodiment the lower plate of the proposed lighting device has a plurality of through apertures distributed therethrough, such as in accordance with a regular pattern, with its skirted edges and corresponding seals, and said illumination device comprises a plurality of LEDs, at least one per aperture. The fact that optical refraction elements, such as lenses, are fixed to the inner face of the lower plate, on the one hand provides a pleasing appearance while, on the other hand, makes assembly easier. The illumination device proposed by the first aspect of the invention has, for a preferred embodiment, a flattened shape, wherein said optical refractive elements are flattened lenses, and said bottom plate is disposed substantially parallel to the circuit board.

To enable the device to generate adequate light, in one embodiment the lighting device comprises a group of at least two LEDs with respective optical refraction elements, wherein each combination of LEDs and optical refraction element belonging to the group is arranged to primarily illuminate the same area of illumination on a lighting surface. As a consequence of this measurement, the light output of each LED in the group contributes to the light intensity of the illuminated area. In this way, the illumination areas generated from each of these combinations only coincide in large part because they are being generated by combinations situated in close proximity to each other.

In the interests of simpler manufacture, and to simplify the technical calculations of light, it is preferred that the LEDs belonging to a group are attached to the same surface. The optical refracting elements belonging to the group are joined with said inner face of the bottom plate, extending outwardly parallel to the surface of the support. In fact this facilitates that the LEDs and optical elements are as parallel to each other as reasonably possible, so that their combined generated beams are also parallel. 5

For one embodiment the lighting device proposed by the invention comprises two or more refractive elements integrated within a multi-stage optical element covering one of said apertures, in front of at least two LEDs. The assembly of the device is further simplified when the group of refraction elements which must be brought together between the bottom plate and the holder includes the group of LEDs which must also be brought together.

Although it is not excluded that the illuminated area to be illuminated by the electrical device is primarily round or square, for one embodiment each of the combinations of LEDs and refraction elements in the group are arranged to illuminate an oblong illumination area, for example , when illuminating streets. In this way, the illuminated area itself will extend mainly along the longitudinal direction of the street.

For another embodiment the LEDs are arranged to illuminate an asymmetrical illumination area.

Lighting devices for street lighting, such as poles, are often placed on the edge of a sidewalk or your premises are attached to a building. In such applications it would be desirable for the device to be placed off center while still providing excellent street and sidewalk lighting.

Optical losses in the optical refraction element occur, in part, as a result of reflection. To avoid this phenomenon as much as possible, it is preferred that at least one of the active optical surfaces of a refractive element be covered with an anti-reflective coating. Therefore, it is possible that this coating is applied to the inner side, to the outer side, or to both sides. The advantage of the inner side coating is that it would be better protected.

To change the light emitted from the LEDs before exiting the refraction element, the preference would be for at least one of the active optical surfaces of the refractive elements to be coated with a phosphor layer. It should be understood that the word " match " means in this case a material which, under the influence of light, emits light at a different wavelength from its received light.

Although in principle a high light production can be achieved by the application of the LEDs without the use of reflectors, the light output is improved when a reflector, preferably a small reflector, is applied by being molded around the conical collar of the LED. The assembly of the device is simplified when more than one optical element of refraction belonging to a group are joined to form a single component.

Although most combinations of LEDs and optical refractive elements are arranged to generate coincident illuminated areas for one embodiment in order to provide greater illumination intensity around the edges of an illuminated area, the lighting device of the invention provides some combinations of LEDs and optical refractive elements arranged just to illuminate these areas of the edge. With respect to this subject, there is provided an embodiment wherein the device includes a number of secondary combinations of LEDs and optical refraction elements, which do not belong to the main group, arranged for illumination of a diverging illuminated area.

For one embodiment, at least some of the combinations of LEDs and optical elements not belonging to the secondary group to be arranged to illuminate the illuminated secondary area, form part of the illuminated area. In this way, the areas around the edge of the illuminated area can be better illuminated. This does not rule out that the illuminated secondary area itself extends out of the illuminated area. In order to decrease the operating temperature of the LEDs and hence extend their service life, for an embodiment of the invention the LED holder is made of suitable thermocouple material and then contacts (preferably by means of a large surface of the device housing in order to transfer the heat from the LEDs and other possible components to the at least one lid which is also made of a good heat-conducting material to act as a heat sink. It is also not to be excluded that the carrier is shaped to form part of the shell. It is worth noting that these brackets are produced as printed circuit boards in many cases. The surface upon which the components are to be placed needs to be fabricated from a type of thermal insulation material so that functional conductive rails can be placed thereon. This essential measurement is combined with that of the present embodiment by a so-called " metal core " printed circuit board. It will soon become clear that other printed circuit boards, entirely made of electrically insulated material, could also be applied.

In the interests of efficient refrigeration, a clean cooling surface is important. In order to keep the cooling surface of the device as clean as possible without effort, it is preferred that the housing is designed with the surface smooth or partially flat. It will soon be clear that the design of a smooth cooling surface should be applied to devices that are equipped with LEDs as light sources; this measurement also needs to be applied to devices for different light sources such as steam lamps.

According to one embodiment of the invention, the proposed lighting device comprises a coupling means (such as a hinge and a connecting piece) for removably attaching its cover and lower plate in a sealed manner.

A second aspect of the invention relates to street lighting comprising the illumination provided by the first aspect, attached to a post with said cover and said lower plate remaining parallel or inclined with respect to the area to be illuminated.

Throughout the description and claims the word " comprises " it is not intended to exclude other technical characteristics, additives, components or steps. 9

Further objects, advantages and features of the invention will become apparent to those skilled in the art upon examination of the description or may be learned by practicing the invention. The following examples and drawings are provided by way of illustration and are not intended to be limiting of the present invention. In addition, the present invention encompasses all combinations of particular and preferred embodiments described therein.

Brief Description of Drawings

Thereafter, the present invention will be explained on the basis of the accompanying drawings, in which the following is shown:

Figure 1: a schematic cross-sectional view of a device according to the invention;

Figure 2: a schematic cross-sectional view illustrating more details of the device shown in Figure 1;

Figure 3 is a schematic cross-sectional view of a second embodiment corresponding to Figure 2;

Figure 4 is a cross-sectional view of a third embodiment, corresponding to Figure 2;

Figure 5 is a cross-sectional view of a fourth embodiment, corresponding to Figure 2; 10

Figure 6 is a cross-sectional view of a fifth embodiment, corresponding to Figure 2.

Detailed Description of Specific Embodiments The device shown in Figure 1 is attached to a post 3 by means of a rod 2. The device 1 comprises a bottom plate 4, which is provided with a regular pattern of apertures. In each of the apertures 5 an optical refraction element 6 is installed. These apertures 5 each have a stepped edge 7 in which the optical elements 6 are held laterally. Between each of the optical elements 6 and the scalloped edge 7 is installed a seal 8. The embodiment illustrated herein comprises a flat device which extends horizontally. However, it is also possible that a similar device could extend at a slight angle. The lower plate 4 of the device has a raised edge, within which is placed a printed circuit board, with the LEDs 11 located on the lower side thereof. On the upper side of the printed circuit board 10 are mounted components 12 such as an actuator circuit to ensure that the LEDs are being fed with the correct current and voltage. The components 12 could also be mounted on the underside of the printed circuit board 10. It is also possible to use the circuit which is not mounted on a printed circuit board 10 for the purpose of driving the LEDs 11. In this way, the circuit board printed circuit 10 is retained between the raised edges 9. The placement of the LEDs 11 on the printed circuit board 10 is such that the LEDs 11 are mounted precisely above the void space created by the optical elements 6. The device 11 comprises a cap 13 which is connected to the edge 9 by means of a hinge 14, opposite which a connecting piece 15 is situated in order to seal the inner part of the device. Of course, tamponade can be used.

Note that the upper side of the cap 13 is smooth. This results in possible contaminations such as bird droppings being washed more easily when it rains, so that the cooling surface is better maintained than would be the case with the usual cooling fins. Such cooling fins would quickly accumulate dirt, while the rain hardly has the potential to do this cleaning. The printed circuit board 10 is equipped with a metal core, preferably made of aluminum, to effectively conduct the heat produced by the LEDs 11 and the components 12 to the printed circuit board 10, where heat can be transferred to the cap 13 , is similar to the rest of the equipment and preferably is also made of a metal such as aluminum. The bottom plate 4 also serves as a heat sink; given its large surface area, which is also finished smoothly and also exposed to environmental conditions. It stands to reason that a device that is mounted on a slope still benefits from this cooling characteristic where inclined surfaces lead to even better cleaning because of rain. This measurement may also be performed in other configurations, such as with other forms of the holder 10 or when the holder 10 extends at various angles. Figure 2 shows in more detail an optical refraction element 6, i.e., a lens. From this drawing, it is evident that there is an empty space 20 in the optical element 6 in which the corresponding LED 11 extends at least partially. On the one hand, this empty space forms a surface with a refractive function, and on the other hand includes part of the LED 11, whereby a large part of the light emitted by the LED 11 is collected by the optical element 6 and is used effectively.

The same parts are illustrated in Figure 3, but in addition the outer part of the optical element 6 is covered with an anti-glare coating, whereby the border reflection losses are greatly reduced. It is also possible that the anti-reflective coating can be applied only to the interior, or on both sides.

The same parts are illustrated in Figure 4, but here, the inner surface of the optical element 6 is covered with a phosphor layer to change the color of the light in the same way as in the case of a discharge lamp, and in particular as used in a fluorescent lamp. Figure 5 also illustrates the same parts, but here a reflector in the form of a collar 23 is mounted around the LED 11. Because of this the light output of the LED 11 is used even more effectively. Figure 6 shows a multistage optical element 24 which performs the function of three independent integrated optical elements, simplifying assembly and reducing the number of parts. 13

It should be understood that a large number of changes may be made to such embodiments without departing from the scope of the invention as defined in the appended claims. 14

Claims (12)

A lighting device for illumination of external public areas, of the type comprising: - a cover (13) and a bottom plate (4) mutually engaged to form a housing, said bottom plate (4) having a plurality of through apertures distributed therethrough; - a holder or circuit board (10) disposed within said housing; a plurality of light emitting diodes or LEDs (11), at least one per aperture, mechanically attached to said circuit board (10) and electrically connected to the circuit defined therein, for emitting light through said apertures (5); - a plurality of refractive optical elements (6) attached to said lower plate (4) covering said through apertures (5), for guiding the light emitted by the LEDs (11) to a lighting area on a surface of lighting outside said housing; said illumination device being characterized in that said lower plate (4) has, at its inner face, around each of said through apertures (5), a recessed portion of the perimeter forming a stepped edge (7) within which a seal 8 is installed, so that the inner surface of each optical refractive element 6 is flush with the inner surface of the lower plate 4. 1 Lighting device according to claim 1, characterized in that said through-openings (5) are distributed along said lower plate (4) according to a regular pattern. Illumination device according to any one of the preceding claims, characterized in that said circuit board (10) is of a thermocouple material and in that it contacts at its edges the housing of the device in order to transfer the heat of the LEDs (11) and other possible components (12) for at least said cover (13) which is also made of a good heat-conducting material to act as a heat sink. Lighting device according to any one of the preceding claims, characterized in that it comprises coupling means (14, 15) for releasably coupling said cap (13) and said lower plate (4) in a sealed manner. Lighting device according to any one of the preceding claims, characterized in that it comprises a group of at least two LEDs (11) with respective optical refraction elements (6) in which each combination of LEDs (11) and optical element (6) belonging to the group are arranged to illuminate mainly the same area of illumination on a lighting surface. A lighting device according to claim 5, characterized in that it comprises at least two refractive elements integrated in a multi-stage optical element (24) covering one of said apertures (5) in front of at least two LEDs (11). Lighting device according to any of claims 5 or 6, characterized in that each of the combinations of LEDs (11) and optical refractive elements (6, 24) in said group are arranged to illuminate an oblong or to illuminate an asymmetric illuminated area. A lighting device according to any of claims 5 to 7, characterized in that it comprises a secondary group or combinations of LEDs (11) and optical refracting elements, arranged for illumination of a divergent illuminated area. Lighting device according to any of the preceding claims, characterized in that said lower plate (4) is arranged substantially parallel to said circuit board (10) and in that said optical refractive elements (6) are flattened lenses (6). Illumination device according to any of the preceding claims, characterized in that at least one inner surface of said optical refractive elements (6) is covered with an anti-reflective coating and / or coated with a layer of phosphorus. Illumination device according to any one of the preceding claims, characterized in that it comprises a reflector in the form of a conical collar (23 surrounding each LED (11). A street lamp comprising the lighting device according to any preceding claim attached to a post (3) with said cover (13) and said bottom plate (4) remaining parallel or inclined to the area to be illuminated 4